The present disclosure relates to a press-fit sleeve for inserting into a fire deck opening of a cylinder head of an internal combustion engine. In particular, a press-fit sleeve for sealing and cooling a component protruding through a fire deck opening in the cylinder head of an internal combustion engine and a corresponding cylinder head are described.
Known cylinder heads of an internal combustion engine have, per cylinder, at least one dome which is intended for receiving a spark plug or an injection nozzle. Each dome is surrounded by a cooling liquid chamber. Document DE 41 19 594 C2 describes such a cylinder head for an internal combustion engine.
Threaded sleeves are ever more frequently used for the spark plugs or the injection nozzles in the cylinder head. In comparison to the cast-on dome, the use of a sleeve improves the cooling of the spark plug or of the injection nozzle significantly because of a thin wall and good heat conductivity of the sleeve. Furthermore, the production of such cylinder heads is simpler.
Such sleeves are customarily screwed into the fire deck of a cylinder head. The external thread of the sleeve and the internal thread on the fire deck are sealed here. In the upper region, the sleeve is mounted freely and is sealed by means of an O ring. Such a conventional sleeve is readily suitable for the use of a diesel injection nozzle since the tip of the injection nozzle is narrow. The injection nozzle itself is introduced from above and does not have any thread at the end facing the combustion chamber.
In contrast to the injection nozzle, a spark plug requires considerably more space in the lower region of the fire deck, i.e. in the region facing the combustion chamber. In addition, the spark plug has to be screwed in and unscrewed with a certain torque. When the spark plug is screwed in and unscrewed, there is the risk of twisting the sleeve in relation to the cylinder head, for example of unintentionally unscrewing the sleeve. As a result, additional working steps arise. Furthermore, the tightness of the thread may be irreversibly damaged.
Moreover, the use of a sleeve requires a greater diameter of the fire deck opening in comparison to the outside diameter of the injection nozzle or of the spark plug, as a result of which the oscillation strength, in particular the flexural fatigue strength and the endurance strength, of the fire deck deteriorate.